In a known optical connector, a receptacle housing is used which, in order to achieve an accurate alignment between a fibre optic ferrule and a opto-electronic conversion element (light emitting element or light receiving element), contains a precision bore to maintain the ferrule accurately in position. In order to achieve the necessary strict tolerances of the fixed bore, it is necessary that the fixed bore of the housing be exactly machined by a precision machine tool. Even if the fixed bore is accurately formed, it does not allow for elastic deformation to accommodate variations in ferrule sizes and manufacturing tolerances associated with the manufacture of the ferrule. It is, therefore, difficult to obtain a standardised optical connector with high reliability of alignment between the ferrule and aforementioned element. Further, since the required accuracy and stability of alignment requires a relatively long connection between the ferrule and the opto-electronic element, and the fixed bore is formed as a cylindrical projection extending from the receptacle housing, relatively high manufacturing costs are associated with such an the optical connector.
In another known optical connector, a precision split sleeve or a hollow tube is employed to connect together two ferrules or to make a connection between one ferrule and an active device on which a dummy ferrule of the same structure as the ferrule is mounted. In order to achieve an accurate alignment, the split sleeve has an inner diameter made slightly smaller than the outer diameter of the ferrules. Since such a split sleeve is always used in a manner which causes the sleeve to expand when fitted onto the ferrules, the diameter of the split sleeve does not have a set, fixed diameter. Because of this, an accurate ferrule-to-ferrule alignment with an adequate pressure force is difficult to achieve.
When the ferrule is connected to the active device, the dummy ferrule is mounted on the forward end portion of the receptacle housing and then needs to be inserted into the split sleeve. Thus an even greater ferrule-to-device connection length is required than in the case of the first mentioned connector type, and the optical connector involves a relatively high manufacturing cost.